Objective-type dark-field illumination for scattering from microbeads.

We introduce a method for detecting and tracking small particles in a solution near a surface. The method is based on blocking the backreflected illumination beam in an objective-type total internal reflection microscope, leaving unhindered the light scattered by the particles and resulting in dark-...

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Bibliographic Details
Main Authors: Braslavsky, I, Amit, R, Jaffar Ali, B, Gileadi, O, Oppenheim, A, Stavans, J
Format: Journal article
Language:English
Published: 2001
Description
Summary:We introduce a method for detecting and tracking small particles in a solution near a surface. The method is based on blocking the backreflected illumination beam in an objective-type total internal reflection microscope, leaving unhindered the light scattered by the particles and resulting in dark-field illumination. Using this method, we tracked the motion of 60-nm polystyrene beads with a signal-to-noise ratio of 6 and detected 20-nm gold particles with a signal-to-noise ratio of 5. We illustrate the method's use by following the Brownian motion of small beads attached by short DNA tethers to a substrate.